The output of such an analog/digital converter generally is an n-bit code word including a sign bit and (n-1) amplitude bits, with n=8 in many instances. The converter may comprise separate circuits, referred to as weighting networks, for respectively quantizing positive and negative analog samples fed to its input. With samples of opposite polarities but the same absolute magnitude, the two weighting networks ought to emit identical combinations of amplitude bits produced by respective groups of individually calibrated current generators.
The conventional technique for checking the calibration of any such current generator is to feed in an analog signal of a predetermined magnitude and to measure the resulting output current. Such an operation, carried out under static conditions for each current generator, is a time-consuming procedure and furthermore does not reveal any irregularities that may arise during normal use of the converter.